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In September 2007, the Audio Engineering Society published the results of a year-long trial, in which a range of subjects including professional recording engineers were asked to discern the difference between SACD and a compact disc audio (44.1 kHz/16 bit) conversion of the same source material under double blind test conditions. Out of 554 trials, there were 276 correct answers, a 49.8% success rate corresponding almost exactly to the 50% that would have been expected by chance guessing alone. When the level of the signal was elevated by 14 dB or more, the test subjects were able to detect the higher noise floor of the CD quality loop easily.

All of Benchmark’s A/D converters and D/A converters support sample rates up to 192kHz. However, we strongly recommend 96kHz for optimum performance. There is a performance penalty for operating at 192kHz. The problem is that all A/D and D/A converter chips operate at reduced oversampling ratios when converting at 192kHz. At the current time, the negative consequences of the reduced oversampling ratio far outweigh any benefits derived from the higher sample rates.

At 192kHz the stopband attenuation of the digital filters is usually much poorer than at 96kHz. Many converter ICs have 120dB of stopband attenuation at 96kHz, but only 80dB at 192kHz. This makes 192kHz converters very susceptible to aliasing and poor image rejection. These artifacts clutter the audible spectrum with low-level non-musical distortion.

It can be shown and demonstrated that there is no loss of time-domain accuracy when operating at 96kHz versus 192kHz. It is a myth that 192kHz gives better time-domain accuracy.

To date, Benchmark has no evidence that 192kHz performs better than 96kHz, but we have a substantial body of evidence that shows that 192kHz has defects that are not present at 96kHz. These issues are also shared openly by one of our competitors: Lavry Engineering. We suspect many other manufacturers are aware of these issues, but choose not to talk about them.

Bottom line: Be very careful about any claims that 192kHz sounds better than 96kHz. Our experience points in the opposite direction.